In recent years, semiconductor integrated circuit elements (IC chips) used for a CPU in computers or the like operate at higher speeds with more high level functional features than previously. Along with this advance, the number of terminals has increased and the terminal interval has tended to be smaller or narrower. Generally speaking, in such a construction, terminals in large numbers are densely formed on the bottom surface of the IC chip in an array, and a terminal block so formed is connected to a further terminal block at the motherboard side by a conventional “flip chip” connection. However, because there is a large difference in pitch between the terminal block at the IC chip side and the terminal block at the motherboard side, it is difficult to directly connect the IC chip to the motherboard. Therefore, the connection method generally employed is one wherein the IC chip is first mounted on a wiring board adapted for mounting the IC chip, and then the wiring board is mounted on the motherboard. An example of such wiring boards for mounting the IC chip includes a wiring board wherein a capacitor is embedded in a core substrate comprised of a polymer material so as to form a core portion, and a built-up layer is formed on both top and rear surfaces of the core portion, respectively (see e.g., Japanese Patent Application Laid-Open (kokai) No. 2005-39243). Further, a wiring board in which the capacitor is built into the insulating layers has also been disclosed (see, e.g. Japanese Patent Application Laid-Open (kokai) No. 2004-228190).
In order to provide stabilization of the power supply by lowering the inductance between the capacitor and the IC chip, the distance therebetween is preferably made as short as possible. Thus, the current thinking in the art is that the capacitor is preferably embedded in the built-up layer located near the IC chip rather than in the core board.